The present invention relates generally to controlling gas flow or gas pressure in a device, and more particularly to a throttle valve assembly for a deposition chamber or the like.
In the manufacturing of semiconductor devices and integrated circuits, multiple layers of different types of materials, such as conductive, semiconductive, and insulation type materials, are deposited or formed on a substrate, semiconductor die or wafer. Selected portions of the different layers may be removed in predetermined patterns by etching, photolithography or other material removal techniques, or ions or charged particles may be implanted in selected areas to form different semiconductor regions and components of a semiconductor device or integrated circuit. In a high volume, high pressure deposition process (HDP) the pressure or flow of gases in a deposition chamber must be precisely regulated or very accurately controlled according to predetermined manufacturing parameters for a particular device or integrated circuit to provide the desired semiconductor structure.
In a high speed operation, the changes in gas flow or pressure must sometimes be made very rapidly as well as with precision. Rapid gas pressure adjustments on the order of one or two nanoseconds may sometimes be required by a particular manufacturing process. The amount of gas pressure within a deposition chamber is typically controlled by a vane or set of vanes disposed within the deposition chamber that can be positioned to completely open, partially open or completely block the flow of gases through the deposition chamber. One mechanical arrangement currently utilized to adjust the positioning of the vanes includes a cylindrical shaft attached at one end to one of the vanes and at the other end, the shaft is inserted into a gear that may be driven by a motor or other means or the gear may drive another gear for positioning another vane of the deposition system. The gear is held in rotational and longitudinal position on the shaft by a set screw. Because the adjustments to the vane or vanes must sometimes be made very rapidly, precisely and under high pressure, the gear is prone to rotational slipping on the cylindrical shaft resulting in the gear becoming offset or misaligned from its proper rotational position on the shaft and resulting in inaccurate positioning of the vanes during a manufacturing process. The misalignment of the gear relative to the shaft and inaccurate positioning of the vanes will cause defective products and manufacturing downtime while the gear and shaft are being realigned. In realigning the gear and shaft, care must be taken to precisely position the gear on the shaft for accurate positioning of the vanes. Misplacement of the drive gear relative to the shaft can also adversely affect the manufacturing process.
Accordingly, for the reason stated above, and for other reasons that will become apparent upon reading and understanding the present specification, there is a need for a throttle valve assembly that is not prone to slippage under extreme operating conditions and that can be precisely and easily assembled for proper alignment of the vanes and accurate control of the gas flow within a deposition chamber or other device.